5.4 (Double and Half Angle Identities)

Question 1

What is sin(2θ)?

Answer 1

2sinθcosθ

Question 2

What is tan(2θ)?

Answer 2

{2tan(θ)}/{1-tan^2(θ)}

Question 3

What are the three variants of cos(2θ)?

Answer 3

cos^2(θ)-sin^2(θ)
2cos^2(θ)-1
1-2sin^2(θ)

Question 4

What is sin(β/2)?

Answer 4

+/- /sqrt[(1-cosβ}/2)], where +/- is based on quadrant

Question 5

What is cos(β/2)?

Answer 5

+/- /sqrt[(1+cosβ}/2)], where +/- is based on quadrant

Question 6

What are the three variants of tan(β/2)?

Answer 6

(1-cosβ)/sinβ
sin/(1+cosβ)
+/- /sqrt[(1-cosβ)/(1+cosβ)], where +/- is based on quadrant